1. Field of the Invention
The invention concerns an improved valve unit for inflating wheels.
2. Present State of the Art
The valve unit that is the subject of the invention is particularly useful for bicycle wheels comprising an inflatable tyre provided with an inflatable inner tube or tubular tyre, wherein the tyre and the internal element are inflated selectively so as to make the tyre shoulders adhere to the rim and thus prevent the tyre from coming off the rim and skidding while the bicycle is running.
The valve unit that is the subject of the invention can be conveniently used also for inflating tubeless tyres or tyres with inner tube or even tubular tyres of the known type comprising an inner tube outside which the casing of a covering element is sewn.
The valve unit of the invention is thus conveniently and advantageously used on touring bikes or racing bikes, on cyclocross bikes or bikes for other types of applications like freeride, cross country, downhill and the like.
Furthermore, the valve unit of the invention can also be used on the wheels of electric bicycles or the wheels of motor cycles of various types.
It is known that in order to inflate tyres of the mentioned types valves are presently used that project from the rim and are connected to a pipe that conveys a pressurized fluid.
If the wheels are provided with tubular tyre or with standard tyre with inner tube or with inflatable tubeless tyre, inflation is obtained using the valve with which tubular tyres, inner tubes or tubeless tyres are provided and which projects from the rim.
If, on the other hand, the wheels require inflation of both the tyre and the inflatable inner chamber, which can be a traditional inner tube or a tubular tyre, two distinct valves projecting from the rim are used, each one of which is in communication with the chamber to be inflated.
Multiple embodiments of wheels of this type are known, all posing the drawback that they need two holes in the rim.
In order to avoid making two holes and thus in order to be able to use standard rims with one hole only, valve units are employed that use the only through hole present in the rim and allow both the tyre and the inflatable chamber present inside it to be inflated.
In particular, patent document U.S. Pat. No. 2,608,235 is known, which describes a valve unit comprising a main tubular body that is arranged so that it passes through the hole in the rim and is provided with a lateral hole in which, using screw means, a secondary tubular body provided with an inflation valve is connected.
In this way, a main through duct is defined in the main tubular body and a secondary duct that communicates with the main duct is defined in the secondary tubular body.
When the valve unit is installed on the wheel, the main duct accommodates the valve of the inflatable inner chamber that passes through it and the secondary duct of the secondary tubular body communicates with the tyre through a tubular chamber that is defined between the main duct and the valve of the inflatable chamber.
The valve body described above offers the advantage that it allows the use of a single hole present in the rim to inflate both the tyre and the inflatable chamber provided inside it but on the other hand it poses some recognised drawbacks.
A first drawback is represented by the fact that the end of the tubular body—at the level of the hole in the rim—features an area with larger diameter that is placed in contact with the inner surface of the rim and projects towards the inside of the tyre.
The presence of said area with larger diameter is indispensable in order to allow the valve body to be fastened to the rim by tightening a threaded nut that is screwed on the outside of the tubular body but constitutes a hindrance and an impediment for the tyre's inner chamber that when inflated cannot adhere well and completely to the inner surface of the rim.
Another drawback lies in that making the valve body in various pieces means increasing production costs, especially due to the need to machine the parts that must be coupled together.
Furthermore, making the valve body in various pieces makes the operations required for assembling the valve body onto the rim longer, more difficult and thus also more expensive.
Finally, the presence of the parts coupled together and of the threaded nuts for fixing to the rim makes the valve body heavier.
The US patent document U.S. Pat. No. 6,354,348 is also known, which describes an inflation valve for tyres that is applied to the valve belonging to the tyre and is arranged so that it passes through the hole present in the rim.
A drawback posed by the valve lies in that it is made up of two parts connected together and to fix it to the tyre's valve it is necessary to use removable mechanical means.
Furthermore, another drawback is represented by the fact that the valve of the invention allows the tyre to be inflated only if said valve is applied to a valve belonging to the tyre.
The US patent document U.S. Pat. No. 1,650,502 is also known, which described an inflation valve that projects from a through hole made in the rim and belongs to two inner tubes provided inside the tyre.
Two inflation ducts are created along the valve body, each one of which communicates with one of said inner tubes, and to fix the valve to the rim it is necessary to use removable mechanical connection means, in the specific case a nut with the relative washer.
Furthermore the valve, in order to allow the inflation of the tyre, must be connected—using further mechanical connection means—to a shaped fitting that houses the unidirectional valves that communicate with the inflation ducts that are present in the valve body and are independent of each other.
Said valve also has the limitation of being fixed to the tyre's inner tube and thus of being suited to allow only the inner tube to which it belongs to be inflated.
Furthermore, the valve described in the above mentioned patent document poses the dual drawback of being made up of two parts that must be connected to each other and of requiring the use of removable fixing means in order to be connected to the rim.
The patent document EP 1 635 095 is also known, which describes an inflation valve that projects from a through hole made in the rim housing the tyre and belongs to an inner tube arranged inside the tyre.
Also this valve has the limitation of allowing only the inner tube to which it is applied to be inflated and thus only a tyre using said inner tube.
Furthermore, it also poses the drawback of requiring the use of removable mechanical means when it has to be connected to the rim.
Finally, it is provided with two ducts for the passage of the inflation gas, wherein said ducts are made in the valve body, are independent of each other and must be connected to a special inflation fitting when it is necessary to inflate the tyre.
The US patent document U.S. Pat. No. 4,171,119 is also known, which describes a valve for tire having a main duct provided at one and of a flared portion. This flared portion is for bonding the valve directly to the tube and is secured to the tube by molding operation and not to the rim. Furthermore, the valve is not in a single body but it is composed with more elements assembled together.